EURELECTRIC views and recommendations on Voltage Quality ...

Monitoring voltage quality: considerations <strong>and</strong> <strong>recommendations</strong>
DSOs measure voltage quality 2 on a regular basis. The monitoring programmes provide data that may
enable smoother network operation, avoid possible faults, ensure better network planning, <strong>and</strong> detect
faults <strong>and</strong> disturbances.
Regulators must take two aspects of voltage monitoring into account:
- The interpretation of such data is not yet harmonised on a European scale; a harmonised format
is needed to ensure a uniform data interpretation across Europe. A st<strong>and</strong>ard template for
reporting data to national regulators would provide added-value to all stakeholders. This
st<strong>and</strong>ard report could include the duration of monitoring campaigns, measurement methods,
phase <strong>and</strong> time aggregation methods for voltage quality events, flagging <strong>and</strong> data exclusion
criteria. The template would result in a uniform report that is independent of recording devices
<strong>and</strong> could serve as a reference for developers of voltage quality management systems looking to
improve reporting tools. The broad adoption of a st<strong>and</strong>ard report would also facilitate voltage
quality benchmarking between European regions. A first step has already been taken with EN
50160:2010, e.g. for a st<strong>and</strong>ardised classification of voltage dips.
- In several EU member states the cost of voltage monitoring is not recognised as a distribution
cost. As a result the DSOs in those countries lack resources to set up proper monitoring schemes.
<strong>EURELECTRIC</strong> DSOs question the necessity of introducing additional voltage quality requirements that
are stricter than the current st<strong>and</strong>ard, as this may lead to higher <strong>and</strong> possibly unnecessary costs for
society, especially because only few customers suffer from voltage quality problems. Moreover, ‘local’
solutions to voltage variations prove to be much more technically <strong>and</strong> economically effective. Therefore
<strong>EURELECTRIC</strong> promotes a wide voltage quality measurement campaign based on EN50160.
Monitoring voltage quality in the LV network: the role of smart meters
Rolling out smart meters opens up the possibility of collecting crude indicators on voltage variations,
interruptions <strong>and</strong> sometimes dips <strong>and</strong> swells at end customers’ connection points. Such indicators could,
for example, show sustained over-voltage <strong>and</strong> under-voltage due to electric cars <strong>and</strong> distributed
generation.
However, such crude data should not be used as a basis for regulatory action. Instead, <strong>EURELECTRIC</strong>
believes that decisions on possible regulatory action should be taken based on the actual impact of
voltage disturbances on customers, as measured by cross-checking voltage disturbances against
customer complaints <strong>and</strong> referenced to the original cause in order to avoid multiple counts or customermade
disturbances. To thoroughly underst<strong>and</strong> <strong>and</strong> h<strong>and</strong>le voltage disturbances, the smart metering
monitoring must be complemented by dedicated <strong>and</strong> sophisticated voltage monitoring devices at
MV/LV substations. It must also be recognised that not all voltage disturbances necessarily result in
negative effects for end-users.
2 Voltage Quality (VQ) covers a wide range of voltage disturbances <strong>and</strong> deviations in voltage magnitude or the voltage
waveform. Examples of voltage disturbances include supply voltage variations, harmonic voltage, voltage dips, <strong>and</strong> other voltage
transients. Generally the MV <strong>and</strong> HV networks are mostly affected by voltage dips whereas the LV networks are mainly affected
by voltage variations, harmonics <strong>and</strong> flicker.
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